This research focuses on union formation among low-income single mothers. Our specific research questions are: 1) How do low-income single-mothers make decisions about union formation and what are the main factors considered? What role do children from current and former unions play in these decisions? and 2) What do "new" families look like after transitions into marital and cohabiting unions? What implications do these "new" family types have for family dynamics (e.g., domestic violence, parenting and step-parenting), economic and material resources (e.g., material hardship), and child well-being (e.g., behavior problems)? Particular attention is given to the implications of complex family arrangements resulting from multiple partner fertility (i.e., having children with more than one partner) for union formation decisions and its consequences. Most union transitions among low-income individuals involve existing children-joint children, her children, his children, and a mix of all three. The implications of this family complexity need investigation. To investigate these questions, we rely on a nested design using panel survey data from the Women's Employment Study (WES) and qualitative data gathered from a sub-sample of WES respondents. Analyses of the WES qualitative data serve as the basis for this application. In turn, qualitative findings are expected to inform hypotheses development that can be tested using the panel data. Scientifically, this research will result in the formulation of new hypotheses and conceptual models on union formation and its consequences for low income individuals. Methodologically, this research can inform future survey data collections by identifying concepts for inclusion when studying marriage and cohabitation among low-income samples and provide guidance in the measurement of these concepts. Results from this research will also inform the design and implementation of marriage promotion programs and policies. [unreadable] [unreadable] [unreadable]